1. Field of the Invention
The present invention relates to a composition, which is resistant to phase separation, comprising a paraffinic polyol chain extender and an isocyanate-reactive prepolymer.
2. Description of the Prior Art
Paraffinic polyols, e.g., the butanediols, have been used as chain extenders in the synthesis of polyurethane compositions. However, it is recognized that such chain extenders, when added to isocyanate-reactive polyols, can produce a composition which is prone to phase separation thereby necessitating a thorough mixing of the polyol/chain extender composition prior to use. This problem of chain extender separation has been solved in certain ways by recent investigators. For example, in U.S. Pat. No. 3,929,730 to P. U. Graefe it is proposed that a butanediol chain extender be combined with at least one other difunctional chain extender which is soluble in the polyol. B. G. Barron in U.S. Pat. No. 3,993,576 teaches use of an effective quantity of a derivative of butylene glycol or propylene glycol as a ccompatibilizing agent. In U.S. Pat. No. 4,220,732 to R. L. McBrayer it is proposed that phenyldiethanolamine be combined with a butanediol chain extender prior to its addition to the polyol.
When a paraffinic polyol chain extender, e.g., a butanediol, is combined with an isocyanate-reactive prepolymer containing hydroxy and epoxy moieties, a similar problem of phase separation has occurred.